The focus of this R21 Pilot and Feasibility Clinical Research proposal is to use transcutaneous electrical nerve stimulation (TENS) for the novel indication of treating neuromuscular activation in knee osteoarthritis (OA) patients that exhibit neuromuscular activation deficits. The overall goal is to improve outcomes associated traditional therapeutic exercise (TE) by developing an enhanced rehabilitation strategy, which augments TE with TENS (TENS+TE), for the purpose of treating underlying neuromuscular activation deficits. Approximately 75% of knee OA patients have neuromuscular activation deficits that lead to disability and impede strength gains that can be achieved with TE interventions. Based on the applicant's prior published work, conducted in a highly controlled laboratory, TENS excites neural pathways that immediately increase neuromuscular activation; also, TENS+TE produces sustained improvements in neuromuscular activation and greater strength gains in knee OA patients compared to traditional TE. There is a need to translate the enhanced rehabilitation strategy into community-based physical therapy (PT) clinics, where TE typically occurs, to improve the benefits of non-surgical rehabilitation for knee OA patients. The objective of this R21 is to report the feasibility and determine the preliminary effects of using TENS to target neuromuscular activation deficits and enhance the traditional TE provided to knee OA patients in PT clinics. We will evaluate the effect of TENS+TE on muscle strength, neuromuscular activation, gait biomechanics, physical function, physical activity, self-efficacy of physical activity, self-reported quality of life, disability and pain. The central hypothesis is tht an enhanced TENS+TE intervention will lead to better clinical outcomes, increased physical activity, and improved general health. The rationale for conducting a small clinical trial, which demonstrates the feasibility and establishes the preliminary effects of an enhanced rehabilitation strategy, is ultimately to inform the development of a future larger clinical trial to establish th efficacy of an enhanced rehabilitation strategy for knee OA. This hypothesis will be tested through two specific aims: 1) to collect and report feasibility data for conducting a future randomized clinical trial to evaluate the efficacy of using TENS+TE compared to sham TENS+TE and to TE only in patients with knee OA, and 2) to determine preliminary effects of a 4-week TENS+TE intervention compared to sham TENS+TE, and TE only on muscle strength, neuromuscular activation, gait biomechanics, physical function, physical activity, self-efficacy of physical activity, self-reported quality of life, disability, and pain in knee OA patients. Posttess will be at 4 and 8-weeks following baseline. This approach is innovative because it introduces a novel indication for TENS and simultaneously develops a new, enhanced rehabilitation paradigm that targets neuromuscular activation deficits, an impairment currently ignored by traditional TE. The results from the proposed randomized controlled trial will be significant for developing a future clinical trial to establish the evidence base for a paradigm shift in knee OA rehabilitation.